Spiral Rib Pipe (SRP) is unique among corrugated metal pipe products. SRP offers the standard corrugated metal pipe (CMP) features of strength, light-weight and durability. SRP has the added advantage of a hydraulic performance equal to that of other pipe products with smooth interior walls. This unique feature of SRP is due to the square ribbed corrugation profile (3/4" x 3/4" x 7 1/2") that projects to the exterior of the pipe. As a result, SRP has a hydraulic roughness coefficient (Manning's "n") of 0.012. This value for "n" makes SRP among the most hydraulically efficient pipe materials available.

SRP with a base metal of steel is available with coatings of galvanized or Aluminized Steel Type 2. It can also be made with a base metal of aluminum for those applications that require the benefits of solid aluminum pipe. An asphalt coating can be applied to any pipe with steel as the base metal. In addition, SRP can be fabricated with a polymer coating (Dow Chemical Trenchcoat) in limited sizes and gauges. SRP is available in round sizes from 15" through 120", and in pipe-arch sizes from 18" through 102".

SRP can be fabricated from a variety of metals and coatings. The basic materials are steel or aluminum. When made of steel the pipe wall is protected with a coating of zinc galvanizing, Aluminized Steel Type 2 or polymer-precoat. These coatings are selected based on the environmental conditions at the installation site. SRP made of aluminum needs no coating to protect it from corrosive elements in the pipe's environment. For more information on selecting the proper base metal or coating, go to the Pipe Selection Guide.

SRP is the best choice for storm sewer applications because of its great strength, excellent hydraulic performance and economy. When combined with Lane's HDPE pipe, the combination offers many advantages to the engineer, contractor and owner.  SRP is also an excellent choice for use in relining applications because of the same advantages it offers in storm sewer projects.